Cut around the pattern pieces, leaving excess around each piece. I don't worry about cutting on the actual lines until I cut the fabric.

Most of the pattern pieces are cut on the fold, so we're going to fold the selvages into the center of the fabric to form a cutting layout with two folds.

Start by folding the fabric in half lengthwise, selvages together. You want the right sides of the fabric to be together--it can be a little difficult to discern the right side of jersey. Look closely at the fibers, and one side will be smoother than the other. This is the right side.

Make sure there are no ripples in the fabric. If there are, re-align the selvages until the ripples or twists are eliminated.

Lay the fabric out on a flat surface and place pins along the fold. These pins will serve as a guide in the next step.

Take each selvage and fold it in to meet the pins.

Your selvages are now meeting in the middle, and you have a fold on either side of the fabric.

Smooth out any wrinkles.

Pin your pattern pieces to the fabric, like so:

All pieces are placed on a fold, EXCEPT for the bra piece. This should be placed parallel to the fold, like so:

Cut the pieces out, so that you're just cutting away the lines for your size. A rotary cutter is a great choice for slinky knits, since you don't have to lift or move the fabric to cut it.

Watch out for kitty paws!

You'll notice that there's a cutting line for the slit on the slip front. Ignore this for now.

Now that all your pieces are cut out, it's time to mark them. Start with the notches. Snip into the point of each notch, leaving a tiny slit. There's no need to cut out the whole notch.

Next, mark the darts on the bra piece. My favorite way to do this is to snip into each dart leg (like you did with the notches) and stick a pin through the end point of the dart.

Mark the end point of the dart on both wrong sides of the piece, using the location of your pin as a guide. Here you can see where my pin is exiting the fabric on the wrong side. I just made a tiny pen mark there.

Finally, use a ruler and a marking pen to connect the slits from your dart legs with the dart endpoint. Voila!

Use a pin to mark the strap placement mark on the bra piece and the slip back.

There's also a square to mark in the upper right corner of the upper back piece.

Now for the slit. The slit is only on the left side of the slip, so you only need to mark that side.

You'll want to mark your upper layer, which will be your left side as you wear the slip (assuming you folded your fabric correctly, with the right sides together. I'm sure you did, though.) Snip into the legs of the slit, as you did for your dart. Place a pin at the endpoint of the slit wedge, and at the large circle mark above it.

On many knit fabrics selvage is more taught than the fabric (looking at your layout picture that is the case) so it is smart to klip notches into selvage for every 10...15 cm to help it stay aäas flat and smooth as possible.

Nice demo! I'll have to get a pen like that since I tend to sling-shot pins out of knits when I sew I also have to admit that I am terrible at that type of layout (2 long folds on grain), maybe it's the cat who wants to help. Anyway, I was told that if I cut out my pattern first on folded paper, then opened that up, I wouldn't need to place the pattern on a fold, whew, that works out so much better for me now, so I'm passing this tip on.